The anwser is number 2 I think,
Hope it helps!
Answer:
For example, delays in mitosis are often ascribed to 'activation' of the mitotic checkpoint, a descriptor that fails to recognize that the checkpoint by definition is active as the cell starts mitosis. Conversely, the completion of mitosis in the presence of misaligned chromosomes is often automatically interpreted to indicate a defective checkpoint, even though in the absence of critical testing alternative interpretations are equally likely. In this article, we define the critical characteristics of checkpoints and illustrate how confusion generated by the inconsistent use of terminology may impede progress by fostering claims that mean very different things to different researchers. We will illustrate our points with examples from the checkpoint that controls progression through mitosis
Explanation:
The answer is reproductive isolation. Reproductive isolation ensures members of different species do not produce offspring. In this case, geographical separation is ensuring that individuals from the two different populations are not able to mate with each other. Eventually, through different selective pressures, the two populations will diverge sufficiently in genotype to become distinctly different.
because fossil fuels take forever to be created hope this helps